--- In TekScopes@..., Glydeck <glydeck@...> wrote:

This is just funny! Stumbled across this and laughed!

Item # 130969457970

Or

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=130969457970&fromMakeTrack=true&ssPageName=VIP:watchlink:top:en



Sent from my iPad

On 17-Aug-13 10:10 PM, tontaub wrote:

 

Hi Don,
no, in particular I was referring to something like a TDS2014C:
http://www.tek.com/oscilloscope/tds2000-digital-storage-oscilloscope
And I agree, this small amount of data storage made me wonder, also because of this I started this thread.
But David made it clear with the examples he showed how this is intended to work.
To find a glitch like I tried to describe in a straight forward fashion by sampling the entire signal it would take something like
ten times this amount of storage.

[2ms error seen up to the 10th harmonic (i.e. to quantify detail in the time domain) gives 1/0.002 * 10 * 2 = 10kHz Sampling rate. So for a 2s signal I'd need 10k*2 = 20000 samples at least]
I see there are products w/ 20kpts and 100kpts/ch at the same price range of a TDS2014C from a direct competitor of Tek - but I wonder what other implications that products have.

Michael.

--- In TekScopes@..., Don Black wrote:

> I assume you mean a digital storage scope, not a sampling scope that
> needs a repetitive signal. 2500 samples are very few by todays
> technology, I guess you're talking of an era when memory was scarce and
> expensive. With a modern digital scope you can store a long stream of
> data and should find the glitch.

On Sat, 17 Aug 2013 11:28:41 -0000, you wrote:

Could one clip the old caps down to the PCB pads and just solder the new cap bent 90 degrees on top of the pcb pad instead of risking trying to remove from a multilayer board.

--- In TekScopes@..., David <davidwhess@...> wrote:

I have faced this problem replacing capacitors on PC motherboards and
video cards and the new no lead solders which have a higher melting
point only make it more difficult. It can be very difficult to get
enough heat on the board without damaging it to make any progress.

On Mon, 12 Aug 2013 00:05:02 -0700 (PDT), you wrote:

. . .

I will note that I capacitor replacement on this board does take skill and care, even with the right tools.  This board is a 4 layer board, unlike the LVPS which is two layer and that seriously complicates the process.  First, four layers means it take more heat to melt the solder clear through the hole.  Second, if a hole is damaged it will be complicated to find and bridge the buried connections.  I have a hobbyist grade solder sucker (Auyoe 474++) with a temperature controlled tip set at 375 C.  I never force a part nor do I let the tip in place for long.  In a few cases I have had to remove the part by just pulling it out as I heat it up and then suck the hole clear for the new part.  Also, four of the electrolytics are "under" the delay line case.  I am able to remove the screws holding the delay line and slide it to one side or the other to access the board in that area.  I used cable ties to hold the delay line case away from each
capacitor as I worked on it.  A note for those who don't know, the delay line is about 4 feet of shielded cable coiled inside a plastic box.  So its pretty robust but still deserves the respect earned by age.

--- In TekScopes@..., Don Black <donald_black@...> wrote:

I assume you mean a digital storage scope, not a sampling scope that
needs a repetitive signal. 2500 samples are very few by todays
technology, I guess you're talking of an era when memory was scarce and
expensive. With a modern digital scope you can store a long stream of
data and should find the glitch.

On Sat, 17 Aug 2013 12:11:00 +0200, you wrote:

Hi D., Henrik, David,

so apparently it looks like that, for instance, examining a short glitch (some ms) in a
very slow signal (seconds) is most likely not possible in a straight forward manner.
Either the anti-aliasing-filter would smooth it out and/or it simply would fall
between two samples.
So the only chance would be a single shot measurement, possibly triggered by this
error event (glitch) and maybe with some sort of pre-recording to get the complete
section of the distortion.
Either way I can't see it at all nor I can determine the exact position of it
in order to track down its cause.
Do Tek scopes provide anything that would be helpful in that way?

Thanks, Michael.

On 15.8.2013, at 17:51 , cheater00 . wrote:

2500 kHz is not a whole lot if you think in terms of time.
However, it's very likely to be able to characterize a single period
of the wave being sampled. Sampling oscilloscopes only work for
repeating waveforms anyways, unless you do single-shot mode and accept
a very heavy bandwidth penalty.

On 15.8.2013, at 18:23 , Henrik Olsson wrote:

Generally speaking the scope selects a sample rate so that the memory
will last for the duration of the "sweep". Ie, if you select 1ms/div
and there's 10 divisions on your screen the memory will have to last
for 10ms so the scope selects a sample rate of 250k samples per second.

On 15.8.2013, at 18:30 , David wrote:

Using dimensional analysis:

250 samples/div divided by 1s/div = 250 samples / 1 second
total time captured is 1s/div * 10 divisions = 10 seconds

250 samples/div divided by 1us/div = 250 samples / 1 microsecond
250 samples/div divided by 1us/div = 250 million samples per second
total time captured is 1us/div * 10 divisions = 10 microseconds

On 17-Aug-13 8:11 PM, egroups@... wrote:

 

Hi D., Henrik, David,

so apparently it looks like that, for instance, examining a short glitch (some ms) in a
very slow signal (seconds) is most likely not possible in a straight forward manner.
Either the anti-aliasing-filter would smooth it out and/or it simply would fall
between two samples.
So the only chance would be a single shot measurement, possibly triggered by this
error event (glitch) and maybe with some sort of pre-recording to get the complete
section of the distortion.
Either way I can't see it at all nor I can determine the exact position of it
in order to track down its cause.
Do Tek scopes provide anything that would be helpful in that way?

Thanks, Michael.

On 15.8.2013, at 17:51 , cheater00 . wrote:

> 2500 kHz is not a whole lot if you think in terms of time.
> However, it's very likely to be able to characterize a single period
> of the wave being sampled. Sampling oscilloscopes only work for
> repeating waveforms anyways, unless you do single-shot mode and accept
> a very heavy bandwidth penalty.

On 15.8.2013, at 18:23 , Henrik Olsson wrote:

> Generally speaking the scope selects a sample rate so that the memory
> will last for the duration of the "sweep". Ie, if you select 1ms/div
> and there's 10 divisions on your screen the memory will have to last
> for 10ms so the scope selects a sample rate of 250k samples per second.

On 15.8.2013, at 18:30 , David wrote:

> Using dimensional analysis:
>
> 250 samples/div divided by 1s/div = 250 samples / 1 second
> total time captured is 1s/div * 10 divisions = 10 seconds
>
> 250 samples/div divided by 1us/div = 250 samples / 1 microsecond
> 250 samples/div divided by 1us/div = 250 million samples per second
> total time captured is 1us/div * 10 divisions = 10 microseconds

--- In TekScopes@..., David <davidwhess@...> wrote:

I have faced this problem replacing capacitors on PC motherboards and
video cards and the new no lead solders which have a higher melting
point only make it more difficult. It can be very difficult to get
enough heat on the board without damaging it to make any progress.

On Mon, 12 Aug 2013 00:05:02 -0700 (PDT), you wrote:

. . .

I will note that I capacitor replacement on this board does take skill and care, even with the right tools.  This board is a 4 layer board, unlike the LVPS which is two layer and that seriously complicates the process.  First, four layers means it take more heat to melt the solder clear through the hole.  Second, if a hole is damaged it will be complicated to find and bridge the buried connections.  I have a hobbyist grade solder sucker (Auyoe 474++) with a temperature controlled tip set at 375 C.  I never force a part nor do I let the tip in place for long.  In a few cases I have had to remove the part by just pulling it out as I heat it up and then suck the hole clear for the new part.  Also, four of the electrolytics are "under" the delay line case.  I am able to remove the screws holding the delay line and slide it to one side or the other to access the board in that area.  I used cable ties to hold the delay line case away from each
capacitor as I worked on it.  A note for those who don't know, the delay line is about 4 feet of shielded cable coiled inside a plastic box.  So its pretty robust but still deserves the respect earned by age.

--- In TekScopes@..., "bpl521" wrote:
>
>
> Yes, it had thrown me for a bit of a loop. I thought great, what is a matter now, the scope seems to be working fine, how can the 10v reference be reading only ~5v.
>
> I am going to recap the board so will take a bunch of pictures and upload. Hopefully tomorrow. I have it out of the scope and there is quite a few differences in both boards.
>
>
> --- In TekScopes@..., "machineguy59" machineguy59@ wrote:
> >
> > You are right, that board looks different in many ways. Even its color is different than I expect, several parts have been moved and it is coated with a post coat/solder mask that seems more recent than mine. Perhaps it is a later version of the board. You can check the board part number with Google to see if it is recognized. I use that often as a check for misplaced parts. The part number on A2 my board is 670-7281-03. But Tek spared these boards as a complete LVPS power supply so I haven't been able to find a list of alternate board part numbers. Perhaps some of the more expert people here know how to do that.
> >
> > A close look at your board shows that TP201 doesn't appear to have a pin fitted to the PCB land. Nearly all Tek test points had a pin fitted so you could grasp it with a probe. Im guessing you have a late version board that may have been fitted to a 2467 or some other close relative of the 2465.
> >
> > You can set the 10 V reference using J119-4. That is what the manual says to do during calibration (see Service Manual, Page 5-2). But I would still be curious to find what A2 board you have, just for future reference.
> >
> > --- In TekScopes@..., "bpl521" wrote:
> > >
> > > Sorry, meant the A2 board. I have uploaded a picture. It has no
> > > electrical continuity to J119-4 or any other J119 pin nor any pins on
> > > U1300. I will be pulling the board out to see where the pad connects to.
> > > You will note that the PCB differs a bit from other 2465B power supplies
> > > I have seen. Could Tek have mislabelled the board, no other test pin
> > > that I can find. I find it odd as the manual refers to adjusting the 10v
> > > with a multimeter on TP201. This test pin measures 5v, yet J119-4
> > > measures 10v.
> > > TP201
> > > > > > 17628/view?picmode=&mode=tn&order=ordinal&start=1&count=20&dir=asc>
> > >
> > > Cheers
> > >
> > > --- In TekScopes@..., "machineguy59" wrote:
> > > >
> > > > Something is confusing. TP201 is on the A2 board, not the A1 board.
> > > It sits right next to U1300 (an LM324) and should measure 10 volts. If
> > > you found a TP201 on the A1 board tell me how to find it and I will
> > > check mine and report back.
> > > >
> > > > If, instead, you mean TP201 on the A2 board then it most certainly
> > > should be at 10 volts. You can check how its wired with an ohm meter.
> > > Just check for continuity between TP201 and U1300 pin 8. If the scope
> > > is assembled you can also find continuity with J119-4 on the A1 board.
> > > >
> > > >
> > > > --- In TekScopes@..., "bpl521" bpl521@ wrote:
> > > > >
> > > > > Double checking the voltages on J119. All seem to be in spec
> > > including
> > > > > the 10v reference on pin J119-4. What I found puzzling is the
> > > service
> > > > > manual says to adjust the 10v reference from TP201. Well when
> > > checking
> > > > > this pin on the A1 board it is at 5 volts??. Can not find any
> > > reference
> > > > > to PCB board changes around TP201. Back tracing to Pin 14 on the
> > > LM324N
> > > > > confirms there is indeed 10v. Will have to separate the boards to
> > > see
> > > > > where TP201 traces back to . Scope is a B05xxxx. The A1 board I have
> > > > > differs slightly according to the service manual. WOnder if it is
> > > from a
> > > > > different model? Serial number on the board is A-7721-06
> > > > >
> > > >
> > >
> >
>

--- In TekScopes@..., "dc_rawding" <drawding@...> wrote:

So I have been in contact with Alexander. I am posting his reply's to my questions on which type of scope that he sold me. I asked for and received his permission to post his responses to my emails.

*****
Hello Dave,
You shouldn't believe everything you read on the net. First of all, I am not Russian (never set foot in that country); second, I don't live in San Francisco, I wish I could afford it...Thirdly, I don't see anything wrong with charging $80 (not $90) for front covers that are scarce and hard for me to find. Fourthly, if Tek made 2 identical scopes: 2445B & 2465B, and charged an extra $3000 ($6000 for 200MHz 2445B vs $9000 for 400MHz 2465B) to not install a bandwidth restrictor on the faster of the 2, what should stop me from removing speed bumps before I sell them? If Tek took the lazy approach to not designing 2 separate scopes for an octave of frequency capability difference, why should I be faulted for removing the speed restriction? Back in the 1980s Tek's trick was designed with hard wiring, today Tek does the same "pay more for more bandwidth" with a software password for a price difference.
I see I sold you a Tek 2465B on 6/11/13 that had 5894 hours. Why would I keep a record of whether it was congenitally a 2465B or a 2445B upgraded to a 2465B (by removal of its speed limiter) if there would be no way to distinguish from the outside and if it's performing the way it should. Performance is checked during cal. Is it not performing as a 400MHz scope? Is it behaving like only a 200MHz scope?
The short answer is I'd have to look inside, but I'm not ashamed of what I do - I'm proud, and I've done this ever since Tek left me a way to make money by removing their speed bumps. Tek knew I was doing this, as I'd buy 50 labels at a time that say "2465B 400MHz Tek scope". If you buy 1 or 2 such labels, it may be to remove a scratch or a mark, but buying 50 at a time hints at a different aim, so Tek knew, and by not hindering me, I guess I had their blessing to continue. I didn't out myself more because most clients didn't believe this was possible. Perhaps the Israeli who finally outed me, was jealous he didn't discover the possibility first, or that his Israeli customs sat on the scope for about 30 days before clearing/taxing it... Upon discovering what Tek left me capable of doing, he tried to extort some parts out of me, and when I said no, he went online for revenge. I don't mind that it's out in the open now. Enjoy, your scope - you still have a month guaranty left on it (if you don't breach my tamper seals). Alex
****

2nd Response;

****
Hi again Dave,
Keep in mind these scopes can & do retain their calibration for a very long time, even 10 years, although they don't usually go for 10 years without experiencing an operational failure, like say, a dried out electrolytic cap.
The 2445/65 (introduced in 1983) pair was the 1st (to my knowledge) of Tek being lazy about designing 2 separate scopes by just doing 1. The previous generation like 465/475 did not share this design feature/upgrade possibility. I don't think buying screentop logo labels for $16/ea, and handle labels for $8/ea repaid my gratitude for Tek unintentionally offering me the extra paying work. The work is not trivially easy to do. It is on the backside of the A1 board, relatively inaccessible to the novice (or 1 timer) but I got reasonably fast at it after several repetitions. The 2467B also shares the same A1, with a very slight mod for added trigger holdoff range.
Alex
*****

So from what I can tell from the emails, some information that Chuck Harris sent me, and after closely inspecting the labels on my scope, it looks like I have a modified 2445B scope (he would not confirm though). The scope works fine and I doubt I will need to go much over 100 Hz for the work I will be doing with it. So it is less hassle for me to keep the scope.

Still something does not seem right about all of this.

Dave

--- In TekScopes@..., "Patrick Wong" <patwong3@> wrote:

Hi Dave,

1. Look at the low voltage power supply and the A5 board to determine whether the electrolytics appear to be original or have been replaced. Typically new electrolytics of large capacitance value will be physically smaller than original caps 25 years old, so the circular outlines on the PCBs which mark capacitor locations will be much larger than a new part's diameter.

2. If your A5 board has a separate lithium battery, does it look like it was replaced? If it has the battery built into the RAM, see if the RAM has a date code.

3. Does U800 have a heatsink installed?

4. If you paid more than $500 for your unit, see whether it looks like the interior is in top condition and therefore worth the price premium.

5. If part of the justification for the price you paid was alleged low runtime hours, please note that counter can be set to any value your heart desires.

Patrick Wong AK6C

--- In TekScopes@..., "dc_rawding" <drawding@> wrote:

This is interesting information. So I am a recent customer of Alexander Schonfeld. His scopes are a little pricey, but I liked the fact that I could see the scope before I bought one as I live within driving distance of his home and I liked that the scope was calibrated.

I purchased a 2465B from him. I am currently restoring a Tektronix 576. However, I have not looked into repairing or getting to know the layout of the 2465B. So I know from this thread that I need to check the part number on the A1 board. Is there anything else I should be checking for?

Thanks,
Dave